Material And Application Of Sanitary Stainless Steel Union Check Valves

To stop backflow contamination, install a union‑type sanitary check valve at every pump discharge and between process stages. Choose 304 or 316L stainless steel body, welding end connections, and EPDM/SILICON/NBR seals based on process temperature. Sizes range from 1″ to 4″. The spring‑loaded disc closes instantly when forward flow stops, blocking reverse flow without manual action. Inspect disc seating and spring tension quarterly – replace seals annually.

How Backflow Ruins Product Batches

When a pump loses prime or shuts off, downstream pressure exceeds inlet pressure. Product flows backward, carrying residues or particles into the upstream batch – undetectable until lab tests fail. A hygienic non return valve seals the line the moment reverse pressure appears. The union‑type body allows fast access to internal components without disturbing welded pipe connections.

Union‑Type Design with Welding Ends

Standard check valves often require cutting into piping for service. Union‑type construction features a central body that unscrews from the two end connectors, which remain welded to the pipeline. This design permits valve removal in under two minutes – no pipe cutting, no realignment.

• ⏱️ Remove the central body while welded ends stay fixed.

• 🔧 Access disc and spring fully for cleaning or inspection.

• 🔄 Replace seals without special tools or re‑welding.

• ✅ Reinstall restores line integrity instantly.

Material Options: 304 vs. 316L

Body and disc materials are available in SS304 or SS316L. SS304 suits water, oil, and non‑corrosive products. SS316L offers superior resistance to chloride‑based CIP agents and acidic foods – the preferred choice for aggressive processing environments. Surface finish Ra ≤ 0.8 µm minimises bacterial adhesion. Spring material is AISI 302, chosen for fatigue resistance over millions of cycles.

Seal Selection by Process Media

The valve accepts three common elastomer seals. EPDM handles dairy and juices up to 135°C. SILICON performs well in dry‑heat applications and offers flexibility at low temperatures. NBR is selected for oil‑based products and greases, with a range of –30°C to +100°C. Each seal type meets FDA requirements for food contact.

Installation and Cracking Pressure

For a hygienic check valve, installation orientation directly affects cracking pressure and seating reliability. A check valve sanitary design works in horizontal or vertical (upward) lines. Cracking pressure – inlet pressure needed to open – varies by size: for 1″ about 0.3 bar, for 4″ about 0.08 bar. Lower cracking pressure saves pump energy. Eccentric disc designs perform better in horizontal pipes – gravity assists seating when flow stops.

CIP Compatibility and Self‑Draining

Sanitary check valves support Clean‑in‑Place without disassembly. Crevice‑free geometry and polished surfaces allow CIP fluids to reach all wetted areas. Self‑draining designs prevent liquid stagnation. Some valves include a disc perforation permitting minimal circulation, avoiding water hammer and ensuring complete drainage – especially important in welded pipelines.

Installation Points for Welded Systems

Place a hygienic non return valve at pump discharge outlets, between mixing tanks and fillers, in CIP return lines, at pasteuriser inlet and outlet, and in multi‑product manifolds. Welded connections eliminate threaded or clamped joints, reducing potential leak paths in high‑purity lines. The union body still allows maintenance without cutting welds.

Maintenance Schedule

Visual checks catch early degradation. Examine disc surface for scoring, spring tension for delay, seal condition for swelling, and body for external leakage. Quarterly disassembly and inspection is standard in high‑volume facilities. The union‑type design turns this into a 15‑minute task, not an hour‑long shutdown – even with welded end connections.

Frequently Asked Questions

Q: What if the valve fails to close completely?
A: Incomplete closure causes back‑siphonage invisible during production. Regular spring tension testing and disc inspection catch this before contamination.

Q: Can these valves handle particulate products like soups?
A: Yes – choose larger clearances for suspended solids. For abrasive products, hardened disc surfaces or replaceable seat inserts extend service life.

Q: Why choose welding ends over Tri‑Clamp?
A: Welded connections are permanent, eliminating gaskets and clamp maintenance. They suit high‑pressure or high‑temperature lines where leakage must be minimised. The union body still provides service access.

Q: What pressure rating is typical for 1″‑4″ sizes?
A: Most sanitary check valves in this range are rated to 10 bar (145 psi). Higher ratings available on request for specific applications.

The union‑type sanitary check valve with welded ends protects every batch from invisible contamination – automatically, reliably, with minimal maintenance interruption.

Sanitary Stainless Steel Union Type Check Valve

• We manufacture Sanitary Tri Clover Check Valve, Hygienic Welding Check Valve, Sanitary Male Check Valve, Sanitary Union Type Check Valve, Hygienic Flanged Type Check Valve.
• Check valve can prevent the fluid from flowing back and ensures that it flows in only one direction.
• It can be used to prevent the less of prime of the pump and to avoid pipe-hammering.
• It is used in the food-processing, beverage, wine-making, oil-making, cosmetics, pharmaceutical and chemical industries.
• The valve opens when the pressure of the fluid exceeds the pressure exerted by the pump spring. 
• When the two pressures are equalized, the valve closes. A stronger counter-pressure allows the valve to close.

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